In a disc drive apparatus for recording and/or reproducing on or from a disc-shaped recording medium such as an optical disc or a magneto-optical disc, using the optical or magneto-optical recording and/or reproducing method, for example, it becomes necessary to perform a so-called track-jump in which the recording and/or reproducing head is to be moved rapidly along the radial direction, as when seaching a desired data, number or image, or when performing a specialized playback or reproducing operation, such as slow reproduction. This track-jump is classified into a medium to long distance jump over several or more tracks and a track-by-track-jump. Even in the medium to long distance jump, a track-by-track-jump ultimately becomes necessary to perform for positioning the head on the target track.
For effecting the track-jump, the conventional practice is to cancel the so-called tracking servo and to supply track-jump drive pulses, composed of acceleration and deceleration pulses, to for example, a head shifting device. Inasmuch as the servo is deenergized temporarily during such track-jump, safety problems are presented, while a deficiency may arise that it takes long time until the tracking servo starts its operation effectively directly after the head arrives at the target track.
In view of the above described problems of the prior art device, it is an object of the present invention to provide a track-jump device for a disc drive apparatus wherein a stable operation may be provided without deenergizing the tracking servo at least at the time of track-by-track-jump.